Brad1234

I know it seems odd, but I have tried it on 2 separate pairs and it made the bass depper and better with foam on both. First I swapped the original foam to insulation on a pair of utility cabinet OLAs and they had less bass response, so swapped back to the foam on them. Then I had 2 sets of OLA's and noticed the bass deeper on the set with foam over the set with insulation. All other variables were the same, newly refoamed woofers and well sealed cabinets. It had to have been the foam increasing the bass, these were just my findings so sharing with group.

I used high density foam like they use for couch seat cushions (actually it was some old couch seat cushions I had kept for reusing when we got a new couch), the newer original Large Advents had 12"x12"x2"-3"? squares of high density foam, I think 3 behind tweeter and 2 behind woofer for the dampening, so I just tried to copy that. If anyone remembers the foam size and number of blocks for Large Advents feel free to chime in. New foam sheets 2"-3" thick run about $40-50, so for my experiment I just cut the foam couch cushions to fit in the OLA, they exactly matched the OLA foam in density, color and weight. I didn't get any good pics of the foam dampening, here are some from my OLA's with original foam in them that I could find.

I wanted to share with the group my experience with restoring 2 pairs of OLA's, one with fiberglass insulation (early pre-1975 version 1 xover) and one with foam in cabinet (post 1975 version 2 xover). I did a full restoration with new caps and resistors, new inductor to replace "red-dot inductor" that is prone to failure, woofers fully rebuilt with reglued and sealed masonite and new foams, and sealing of drivers to baffle with foam weatherstripping. After setting all 4 up for A/B comparison and trying out stacking, it was clear the fiberglass insulation earlier model had noticeably reduced bass and flat, tinny sound compared to the newer OLA with foam stuffing. All things were equal between the 4 speakers except cabinet stuffing (though woofers do look slightly different, see pics) and all were well sealed with slowly returning woofer when pushed in. I decided to try out swapping the fiberglass for foam stuffing in the cabinet and, wow, the difference in bass response is incredible! The foam sounds so much better than fiberglass. Deeper bass and the mids sound warmer and more clear as well. I guess there was a reason Advent switched to foam stuffing over insulation sometime before 1975. See pics and let me know what u think?

I use the partsexpress black rope caulk for woofer sealing. U have to shape it a little by gently pulling on it to thin it for the smaller drivers. It is sticky but not messy, excess easily scrapes off baffle and wont stain if removed soon after install. The area smashed under the drivers stains and "impregnates" the baffle, but it is easy to scrape off old and put new right back over old residue, no cleaning necessary. Super easy to remove driver and redo seal as much as u need to. I have removed and replaced the drivers like 4 times for various repairs/adjustments on my 5's, often just reshaping and re-using old rope caulk.

Thanks Jkent for the post! I made sure to dope all of the drivers when restoring them with VintageAR sealant. They look so beautiful all shiny and freshly doped! I did add a second layer to the mids just to see if it helped, I think it may have but hard to tell. When I push on one mid the other mid moves up, so they are pretty well sealed. Question, how often do they need to be redoped? My other Model 5's were doped about 8 months ago and their mids look a little dry, so I was going to add another coat to them too. The woofer looks ok though. Maybe that will help with the difference in sound between mids.

Quick clarification on the "white dot" settings in the restoration manual. I recently installed brand new 16 ohm pots (not Lpads w/ resistors) on my AR-3a's that I got from JKent for a great price and I installed them with the white dot lined up with 8ohms to center it. After checking the manual, the white dot settings are listed at 3.25 ohm for mid and 1.75 ohm for tweeter. This would mean the factory settings for the pots had them turned over 3/4 of the way to full volume on mid and tweeter? Just wanted to make sure I interpreted that right from the manual, the speakers do sound best with the pots cranked up to around 2-3 ohm output (almost full blast). Also, I assume the ohm setting is based on the pot not hooked up to the crossover when measured?

Update on this post, I think I figured out the issue I have been having with my Model 5's, it is my Marantz 2270 receiver, it needs a recap. The mids coming out of it are not sounding right. After switching receivers, the 2 pairs of Model 5's sound more similar to each other, but the new gold colored mids do have a slightly lower frequency response than the silver ones, but both sound good.

Hi All, I am restoring my second pair of Model 5's and after finishing them, the mids sound a lot different from my older pair and have been trying to figure out why. The first pair I restored have lower numbered silver-colored sticker SN's and date stamped 1968, so I assume they are older than the second set I restored with higher #'s and paper sticker, let me know if that is wrong? At first I thought the sound difference was the different inductors on the newer xovers making the mids in the newer restored pair sound much lower in frequency (new caps are exactly the same on both xovers). But I swapped the mids between older and newer restored pair and the mids still sounded lower in frequency in the older pair, so the sound difference is the actual mid speakers. The older mids are silver in color and date stamped 1968 on back. The newer, lower frequency sounding mids are goldish colored. Anybody know if this is a normal thing for the goldish colored mids to have a different sound over the silver ones? I know this is a weird question, but just seeing if any of you KLH experts have noticed this too? I included photos of the 2 different xover networks and the new (goldish) mid vs older (silver) mid speaker side by side.

Update on my previous post on this thread, I re-recapped my AR 3a's from the Jantzen Crosscaps to the Audyn Q4 caps and they sound like completely new speakers, so much louder and clearer with the Audyn caps! There was something wrong with those Jantzen caps, I never really liked them from when I first installed them, and I have had them for about 9 months so they got well burned in with no improvement in sound. I also have newly rebuilt tweeters and new potentiometers, so I suspected caps were the issue and took the plunge to recap them all over, so glad I did. I just wanted to share my experience with the Audyn and Jantzen caps to the group, I have had really good results with several recap jobs with the Audyn Q4 caps (red caps in photo).

Update: just installed the new .45 mH inductor in place of red dot and swapped the 16 for an 8uf cap, so it's officially updated to post 1974 xover and man what a difference in sound!! The mids and highs are soooo much clearer and balanced, and the tweeters are not harsh like they used to be. I don't have a tool to test the old inductor to see if it was burned out or not, but very happy with Pete's suggestion to convert the xover to newer version. Thanks Pete!

Hey Doug, I am usually on the same page about keeping things original, but that red dot inductor is a weird value and I couldn't find what I thought was a suitable replacement for it. Also, I agree with Pete about the Advent increase setting on the switch making the tweeter overly harsh on the original xover design, so anything to tone the tweeter down works for me!!

Hi Steve, the only other 2 things to make sure you do is try hooking the tweeter up to another speaker's tweeter connection at low volume and see if it works? There could be a malfunction in the switch on the xover board, hooking another tweeter or small speaker up to the tweeter leads and seeing if it works will confirm the xover is fine and sending signal to the tweeter. Those r the only 2 fool-proof troubleshooting ideas to confirm it is just a blown tweeter.

Are you sure the tweeter is actually blown and not a crossover problem? I had to recap my Model 5's to get tweeters working. You would have to search ebay for a vintage replacement tweeter if it is blown. Sometimes the voicecoil wire can get disconnected and some solder can reattach it too. That takes lots of troubleshooting, but I have fixed a few not working tweeters that way.

Hi Pete, I decided to build the 16/8/3 newer revision xover for both of my OLA's, it just seemed to complicated trying to replace that 0.8 red dot inductor. I will just have to swap a 16 for an 8 uF cap on the pair I already recapped. The DCR on the new 0.45mH inductor you recommended from partsexpress is around 0.45 ohm, which should be ok? I really appreciate all of yall's help on my questions!

Hi Pete, I have an inductor question, when shopping for them how close do I need to get to the DCR rating for ohms? I think within .20 ohms of target? Most of the inductors are around .45 ohms and the xover schematic calls for 0.25 ohms. Also the red dot 0.8 mH inductor calls for 2.3 ohms, which I cant find. Would I add a resistor to reach that 2.3 ohm level? Sorry for all of the questions, I am still learning about inductors. I am going to try converting one of my pre1974 advents sets to newer crossover and just replace the red dot inductor on my other pair to compare them.